Mold-Cooling System and Mold-Cooling Method

ABSTRACT

A mold-cooling system for cooling a heated mold by supplying cooling medium from a cooling medium supply source to a medium flow path provided for a mold. The mold-cooling system is characterized in that a discharge side path connected to an outlet side of the medium flow path of the mold is communicated with a heat exchanger condensing the cooling medium gasified and discharged from the medium flow path.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a mold-cooling system and amold-cooling method for cooling a heated mold.

2. Description of the Related Art

For cooling a heated mold, a mold-cooling system (a mold-coolingapparatus) supplying cooling medium such as cooling water to a mediumflow path provided for a mold has been known conventionally. In theabove-mentioned mold-cooling system, there has been a problem thatcooling medium supplied to the medium flow path of the mold heated to ahigh temperature gasifies in the medium flow path and the vapor isdischarged. Patent Literature 1 below, for instance, discloses atemperature-control device for the mold constituted in such a mannerthat a conduit pipe for supplying liquid at ordinary temperatures and adrain pipe are connected to a liquid circulating passage constituted byconnecting a liquid passage of the mold with that of a temperaturecontroller, and the conduit pipe for liquid supply and the drain pipeare connected by a throttle passage, thereby supplying the ordinarytemperature liquid passing through the throttle passage to the drainpipe and suppressing generation of the vapor.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2002-52538

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Recently, due to large size of articles to be molded, diversification ofmolding material or the like, a system for cooling the mold at a hightemperature approximately from 150 degrees Celsius to 300 degreesCelsius is desired. In such a cooling system, when cooling medium is fedinto the medium flow path of the mold, the cooling medium instantlygasifies and pressure increases in the medium flow path of the mold;also accompanied with relatively large heat capacity of the mold, it isdifficult to feed cooling medium into the medium flow path of the moldfrom a supply source side of cooling medium, cooling time is prolonged,and a pump of high discharge pressure is required. As shown in PatentLiterature 1, for instance, condensation by supplying liquid to a pathon a discharge side of the mold is also possible; similar to a mediumfeeding side, it is difficult to supply liquid due to the increase inpressure, and the pump of high discharge pressure is required.

In view of the above-mentioned problems, an object of the presentinvention is to provide a mold-cooling system and a mold-cooling methodwhich suppress discharge of gasified cooling medium and enhance coolingefficiency.

Means of Solving the Problems

In order to achieve the above-mentioned object, in a mold-cooling systemof the present invention for cooling a heated mold by supplying coolingmedium from a cooling medium supply source to a medium flow pathprovided for a mold, a discharge side path connected to an outlet sideof the medium flow path of the mold can be communicated with a heatexchanger condensing the cooling medium gasified and discharged from themedium flow path.

In the present invention, a path supplying steam from a steam source orair from an air source can be connected to a supply side path connectedto an inlet side of the medium flow path of the mold from the coolingmedium supply source, and the mold-cooling system can include a controlportion controlling supply of the steam or the air and supply of thecooling medium, and supplying the cooling medium to the medium flow pathof the mold after supplying the steam or the air to the medium flow pathof the mold.

In the present invention, the path supplying steam from the steam sourceor air from the air source can be connected to the supply side pathconnected to the inlet side of the medium flow path of the mold from thecooling medium supply source, and the mold-cooling system can includethe control portion controlling the supply of the steam or the air andthe supply of the cooling medium, and supplying the steam or the air tothe medium flow path of the mold after supplying the cooling medium tothe medium flow path of the mold.

In the present invention, the discharge side path on a downstream sideof the heat exchanger can be provided with a backflow prevention portionpreventing backflow.

In order to achieve the above-mentioned object, in a mold-cooling methodof the present invention for cooling the heated mold by supplyingcooling medium to the medium flow path provided for the mold, thedischarge side path connected to the outlet side of the medium flow pathof the mold is communicated with the heat exchanger, and the coolingmedium gasified and discharged from the medium flow path is condensed inthe heat exchanger.

In the present invention, the cooling medium can be supplied to themedium flow path of the mold after executing a precooling step in whichsteam or air is supplied to the medium flow path of the mold.

In the present invention, a second cooling step in which steam or air issupplied to the medium flow path of the mold can be performed afterexecuting a first cooling step in which the cooling medium is suppliedto the medium flow path of the mold.

Effects of the Invention

The mold-cooling system and the mold-cooling method of the presentinvention, constituted as mentioned above, suppress discharge ofgasified cooling medium and enhance the cooling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system configuration diagram which schematically shows oneexample of the mold-cooling system in one embodiment of the presentinvention.

FIG. 2 is a schematic time chart which shows one example of basicoperation executed in the mold-cooling system.

FIG. 3 is the system configuration diagram which schematically shows oneexample of the mold-cooling system in another embodiment of the presentinvention.

FIG. 4 is the schematic time chart which shows one example of basicoperation executed in the mold-cooling system.

FIG. 5 is the system configuration diagram which schematically shows oneexample of the mold-cooling system in still another embodiment of thepresent invention.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention is explained below with referenceto the drawings. In FIG. 1, FIG. 3, and FIG. 5, pipe lines (pipearrangement), i.e. paths through which medium, or the like passes, areschematically shown in a solid line.

The schematic time charts in FIG. 2 and FIG. 4 diagrammatically show ONand OFF operations, opening and closing operations or the like ofrespective devices.

FIG. 1 and FIG. 2 illustrate a mold-cooling system in a first embodimentand a mold-cooling method carried out with the mold-cooling system.

A mold-cooling system 1 in the embodiment is constituted for cooling aheated mold 2 in such a manner that cooling medium from a cooling mediumsupply source 10 is supplied to a medium flow path 4 provided for themold 2. As shown in FIG. 1, the mold-cooling system 1 is constituted insuch a manner that a discharge side path 15 connected to an outlet 5side of the medium flow path 4 of the mold 2 is communicated with a heatexchanger 20 condensing gasified cooling medium discharged from themedium flow path 4.

In the embodiment, the mold-cooling system 1 is a mold heating-coolingsystem 1 which performs heating in addition to cooling of the mold 2.

The mold 2 is, for instance, constituted with a fixed mold and a movablemold; the fixed mold and the movable mold are respectively provided withthe medium flow paths 4, 4 for circulating cooling medium. A supply sidepath 13 (a medium feeding path) is connected to inlets 3, 3 (mediumfeeding connection ports) side of the medium flow paths 4, 4. Thedischarge side path 15 (a medium returning path) is connected to outlets5, 5 (medium returning connection ports) side of the medium flow paths4, 4.

The supply side path 13 and the inlets 3, 3 of the medium flow paths 4,4 can be connected by a manifold portion which divides a single supplyside path 13 into plurality or by flexible piping members, such as ahose or a tube which is connected to a plurality of connection ports ofthe manifold portion.

The discharge side path 15 and the outlets 5, 5 of the medium flow paths4, 4 can be substantially similarly connected by a manifold portionwhich branches a single discharge side path 15 into plurality or byflexible piping members, such as a hose or a tube which is connected toa plurality of connection ports of the manifold portion.

The mold 2 is provided with a temperature sensor 6 as a detection meansfor detecting the temperature of the mold 2. The temperature sensor 6can be constituted so as to detect the temperature of medium (coolingmedium) on the outlet 5 side, a vicinity region of the outlet 5 of themedium flow path 4, a downstream vicinity region of the outlet 5, or thelike. The mold 2 is provided with a mold heater 7 as a heating means forheating the mold 2. The figure shows an example in which the moldheaters 7, 7 are respectively embedded in the fixed mold and the movablemold of the mold 2.

A target heating temperature (a set heating temperature, referring toFIG. 2) of the mold 2 heated by the mold heater 7 as the heating meanscan be appropriately set according to the size or the shape of anarticle to be molded, the type of molding material or the like and inview of improving fill ability of molten material or transfer property(transfer rate) of a cavity face to the article to be molded. When thearticle to be molded is relatively large in size, the target heatingtemperature can be set relatively high, for instance approximately from150 degrees Celsius to 300 degrees Celsius or approximately from 200degrees Celsius to 300 degrees Celsius.

A target cooling temperature (a set cooling temperature, referring toFIG. 2) of the mold 2 cooled by cooling medium from the cooling mediumsupply source 10, to be mentioned below, can be also appropriately setfrom a similar point of view as mentioned above, from the point of viewof capable of solidifying molten material and shortening a moldingcycle, or the like. The target cooling temperature can be set lower thanthe target heating temperature. However, when the target coolingtemperature is too low, accompanied with large heat capacity of the mold2, time for cooling down to the target temperature and time for heatingup to the target temperature in a next step are likely to be prolonged.From the above-mentioned view or the like, the target coolingtemperature can be, for instance, approximately from 100 degrees Celsiusto 200 degrees Celsius or approximately from 150 degrees Celsius to 200degrees Celsius. When the target heating temperature is set relativelyhigh as mentioned above, the target cooling temperature can be set lowerthan the target heating temperature approximately by 40 degrees Celsiusto 120 degrees Celsius.

A molding machine of the mold 2 can be an injection molding machine orthe like in which synthetic resin, i.e. material molten by a cylinder orthe like, is injected from a nozzle or the like and filled into a cavityor the like formed by the fixed mold and the movable mold of the mold 2,thereafter the article is molded successively. Other molding machinessuch as a compression molding machine can be adopted. Molding materialcan be fiber-reinforced synthetic resin material or the like, i.e.synthetic resin material containing reinforced-fiber such as carbonfiber or glass fiber.

The heating means for the mold 2 is not limited to the mold heater 7mentioned above; it can be a heating medium supply source which suppliesheating medium to the medium flow path provided for the mold 2. In sucha case, the heating medium can be fed into the cooling medium flow path,or an aspect can be such that the heating medium is fed into the mediumflow path exclusively for the heating medium. Other kinds of heatingmeans can be adopted. Furthermore, heating of the mold 2 can beperformed by autothermal of molten material injected into the cavity ofthe mold 2.

As for the cooling medium supply source 10, appropriate supply sourcescan be adopted according to types of cooling medium, requiredtemperatures of cooling medium, the target cooling temperature or thelike. For instance, the cooling medium supply source 10 can beconstituted with a storage portion (a tank) which stores cooling medium,and with a cooling medium supply pump 11 (referring to FIG. 2) whichsupplies (feeds) cooling medium stored in the storage portion towards amold 2 side. In such a case, temperature can be appropriately controlledby a cooler such as a chiller so that cooling medium stored in thestorage portion is maintained at the predetermined temperature.

Cooling medium supplied from the cooling medium supply source 10 isliquid on a supply side and is water (clean water) in the embodiment;alcohol including ethanol, or other cooling medium can be adopted.Cooling medium of which boiling point at ordinary pressures is equal toor less than 100 degrees Celsius can be adopted.

The temperature of cooling medium supplied from the cooling mediumsupply source 10 can be set at ordinary temperatures or can be, forinstance, approximately from 5 degrees Celsius to 90 degrees Celsius orapproximately from 10 degrees Celsius to 50 degrees Celsius. The coolingmedium supply source 10 is not limited to the one as mentioned above andcan have a storage portion in which temperature control is notperformed. The cooling medium supply source can be a cooling tower orthe like installed in a plant or the like, or can be a water supplysystem (industrial water works, water works).

In the embodiment, the mold heating-cooling system 1 is constituted insuch a manner that paths 18, 19 respectively supplying steam from asteam source 8 and air from an air source 9 are connected to supply sidepaths 12, 13 connected to an inlet 3 side of the medium flow path 4 ofthe mold 2 from the cooling medium supply source 10.

The steam source 8 can be a boiler or the like which heats andvaporizes, or gasifies liquid (preferably liquid of the same kind ascooling medium supplied to the medium flow path 4 of the mold 2 from thecooling medium supply source 10) with a heat source.

The steam supply path 18 which supplies steam from the steam source 8 isprovided with a steam valve 18 a such as a solenoid valve which suppliesor cuts off steam from the steam source 8. One end of the steam supplypath 18 is connected to the steam source 8 and the other end isconnected to the supply side path 13 by an appropriate coupling or thelike. The temperature of steam supplied from the steam source 8 can beappropriately set according to the above-mentioned target coolingtemperature, for instance, substantially the same temperature as orlower than the above-mentioned target cooling temperature.

The air source 9 can be constituted in such a manner that the atmosphereor the like is sent by a blower; it can be a compression air source of agas tank or the like which stores gas (high-pressure gas) compressed bya compression machine such as a compressor through an aftercooler, adrain separator, a dryer, or the like.

The air supply path 19 which supplies air from the air source 9 isprovided with an air valve 19 a such as a solenoid valve which suppliesor cuts off air from the air source 9. One end of the air supply path 19is connected to the air source 9 and the other end of the air supplypath 19 is connected to the supply side path 13 by an appropriatecoupling or the like.

The supply side paths 12, 13 which connect the cooling medium supplysource 10 with the inlet 3 of the medium flow path 4 of the mold 2 areconstituted with an upstream supply side path 12 (a cooling mediumsupply source 10 side) further than a connecting portion, as mentionedabove, of the steam supply path 18 and the air supply path 19, and witha downstream supply side path 13 (the mold 2 side) further than theconnecting portion.

The upstream supply side path 12 of the supply side paths 12, 13 isprovided with a cooling medium valve 12 a such as a solenoid valve whichsupplies or cuts off cooling medium from the cooling medium supplysource 10. The cooling medium supply pump 11 as mentioned above isdisposed at the upstream supply side path 12. The upstream supply sidepath 12, the above-mentioned storage portion or the like is providedwith the detection means such as a temperature sensor which detects thetemperature of cooling medium fed into the medium flow path 4 of themold 2; based on the detection value of the detection means, temperaturecan be controlled by the above-mentioned cooler or the like so that thetemperature of cooling medium becomes the predetermined temperature.

The heat exchanger 20, in which cooling medium fed through the dischargeside path 15 connected to the outlet 5 of the medium flow path 4 of themold 2 is high-temperature fluid, is communicated with a cooling path 14into which low-temperature fluid which cools and condenses thehigh-temperature fluid is fed. The discharge side path 15 and thecooling path 14 can be respectively connected to a fluid passage on ahigh-temperature side and a fluid passage on a low-temperature side ofthe heat exchanger 20.

In the heat exchanger 20, cooling medium gasified through the mediumflow path 4 of the mold 2 heated to a high temperature is heat-absorbedby low-temperature fluid which is fed through the cooling path 14,cooled condensed, and liquefied.

In the embodiment, the cooling path 14 is constituted to feed coolingmedium supplied from the cooling medium supply source 10 into the fluidpassage on the low-temperature side of the heat exchanger 20. Namely,the cooling medium supply source 10 which supplies cooling medium to themedium flow path 4 of the mold 2 is constituted so as to be also used asthe supply source which supplies cooling medium to the fluid passage onthe low-temperature side of the heat exchanger 20. As mentioned above,the constitution is further simplified as compared with a case in whichthe cooling medium supply source for the heat exchanger 20 is separatelyprovided.

The cooling path 14 is connected by an appropriate coupling or the likeon the upstream side further than a region for which the cooling mediumvalve 12 a of the upstream supply side path 12 is provided. In otherwords, the upstream supply side path 12 is divided into the supply sidepath 12 heading toward the mold 2 side and the cooling path 14 headingtoward a heat exchanger 20 side on the upstream side further than theregion for which the cooling medium valve 12 a is provided.

The cooling path 14 is provided with a heat exchanger cooling valve 14 asuch as a solenoid valve which supplies or cuts off cooling medium fromthe cooling medium supply source 10. The cooling path 14 is connected toa medium returning side of the cooling medium supply source 10.

In the embodiment, the discharge side path 15 (on a downstream side ofthe heat exchanger 20) connected to the outlet 5 of the medium flow path4 of the mold 2 and passing through the heat exchanger 20 is connectedon the medium returning side of the cooling medium supply source 10.Namely, cooling medium supplied to the medium flow path 4 of the mold 2is circulated in a closed-loop manner with the cooling medium supplysource 10. As constituted above, impurities are unlikely to be mixed andquality control of cooling medium is easily performed.

The figure shows an example in which the discharge side path 15 on thedownstream side of the heat exchanger 20 is connected to the coolingpath 14 on the downstream side of the heat exchanger 20 in a confluentmanner.

In the embodiment, the discharge side path 15 on the downstream side ofthe heat exchanger 20 is provided with a backflow prevention portion 16for preventing backflow.

The backflow prevention portion 16 in the embodiment is a backflowprevention valve (a non-return valve, a check valve) which permits afluid flow from the heat exchanger 20 side into the cooling mediumsupply source 10 side and blocks a fluid flow from the cooling mediumsupply source 10 side into the heat exchanger 20 side. By adopting sucha backflow prevention valve as the backflow prevention portion 16, anopening and closing control or the like becomes unnecessary ondischarging (returning the medium) and backflow is prevented by a simplecontrol, as compared with the conventional one provided with an openingand closing valve or the like as the backflow prevention portion.

As for the above-mentioned heat exchanger 20, heat exchangers of varioustypes such as a double pipe heat exchanger, a plate heat exchanger, ashell and tube heat exchanger, and a cross fin heat exchanger can beadopted. While the figure shows the heat exchanger 20 of a parallel flowtype, heat exchangers of a counter flow type, a cross flow type or thelike can be used.

The discharge side path 15 on the downstream side of the heat exchanger20 (the discharge side path 15 on an upstream side further than thebackflow prevention portion 16) can be appropriately provided with asteam trap or the like if necessary.

While the figure shows an embodiment in which opening and closing valves(ON and OFF valves) are respectively provided to open and close theupstream supply side path 12, the cooling path 14, the steam supply path18, and the air supply path 19, all or some of the above-mentionedvalves can be constituted by a multiport and multi-position typechangeover valve or the like.

The mold heating-cooling system 1 has a control panel 21 including acontrol portion 22 which controls the mold heater 7, the cooling mediumsupply pump 11, and the valves 12 a, 14 a, 18 a, 19 a.

The control panel 21 has the control portion 22 such as a CPU, a displayoperation portion 24, and a memory portion 23, which are respectivelyconnected by signal lines. The display operation portion 24 constitutesa display portion and an operation portion for setting up, inputting ordisplaying. The memory portion 23 is constituted by various memories andstores information about conditions and values inputted and set up by anoperation of the display operation portion 24, various programs such asa control program for executing respective operations mentioned below,various predetermined operation conditions, various data tables or thelike.

The control portion 22 has a timing means such as a clock timer, and anarithmetic processing portion and is connected to the mold heater 7, thecooling medium supply pump 11, and the valves 12 a, 14 a, 18 a, 19 athrough the signal line or the like for controlling. The control portion22 is also connected to the temperature sensor 6 of the mold 2 throughthe signal line or the like.

In the embodiment, the control portion 22 is constituted to control thesupply of steam or air and also the supply of cooling medium.

In the embodiment, as shown in FIG. 2, the control portion 22 isconstituted to control so as to supply cooling medium to the medium flowpath 4 of the mold 2 after supplying steam to the medium flow path 4 ofthe mold 2.

In the embodiment, as shown in FIG. 2, the control portion 22 isconstituted to control and supply air to the medium flow path 4 of themold 2 after supplying cooling medium to the medium flow path 4 of themold 2.

The mold-cooling apparatus constituting the mold heating-cooling system1 could be the one having opening and closing valves 12 a, 14 a, 18 a,19 a disposed at the above-mentioned paths 12, 14, 18, 19, the backflowprevention portion 16, the heat exchanger 20, and the control panel 21as shown in two-dot chain lines of FIG. 1. Furthermore, the aboveapparatus could be the one having at least one of the steam source 8,the air source 9, and the cooling medium supply source 10. In addition,the above apparatus could be a mold heating-cooling apparatus whichfurther has the heating means 7 for heating the mold 2.

In the mold heating-cooling system 1 in the embodiment constituted asabove, the mold 2 is heated when the mold heater 7 is activated. Themold heater 7 can be such that energization control such as a PIDcontrol is performed by the control portion 22 in order that thetemperature of the mold 2 becomes the predetermined target heatingtemperature based on a measurement temperature signal (a detectiontemperature) of the temperature sensor 6 of the mold 2. Theabove-mentioned target heating temperature can be inputted and set upthrough the display operation portion 24.

When the cooling medium supply pump 11 is activated and the coolingmedium valve 12 a is opened, cooling medium from the cooling mediumsupply source 10 is supplied (supplied in circulation in the embodiment)to the medium flow path 4 of the mold 2.

When the cooling medium supply pump 11 is activated and the heatexchanger cooling valve 14 a is opened, cooling medium from the coolingmedium supply source 10 is supplied to the fluid passage on thelow-temperature side of the heat exchanger 20. The opening and closingcontrol of the above-mentioned heat exchanger cooling valve 14 a, suchas the PID control, can be performed by the control portion 22 in orderthat the temperature of returned cooling medium becomes thepredetermined target temperature based on the measurement temperaturesignal (the detection temperature) of the temperature sensor. Thetemperature sensor detects the temperature on the downstream side of theheat exchanger 20 of the discharge side path 15 which is communicatedwith the fluid passage on the high-temperature side of the heatexchanger 20. The above-mentioned target temperature can be inputted andset up through the display operation portion 24.

When the steam valve 18 a is opened, steam from the steam source 8 issupplied to the medium flow path 4 of the mold 2.

When the air valve 19 a is opened, air from the air source 9 is suppliedto the medium flow path 4 of the mold 2.

One example of a mold heating-cooling method (the mold-cooling method)is explained based on FIG. 2 as one example of basic operation executedin the mold heating-cooling system 1 in the embodiment constituted asabove.

In a graph of FIG. 2, a horizontal axis is a time axis, a vertical axisis the detection temperature of the temperature sensor 6, and itstransition is schematically shown.

First, the mold heater 7 is activated and a preheating step can beexecuted to preheat the mold 2 substantially at ordinary temperaturesapproximately to the target cooling temperature. A standby state isobtained when the preheating step is executed as above.

In the molding machine of the mold 2 not shown in the figure, moltenmaterial such as resin is injected and filled into the cavity providedfor the mold 2 in a closed condition, and pressure is appropriatelykept; when molten material is solidified, the mold is opened, and thearticle is demolded. In such a series of molding steps, the moldheating-cooling system 1 in the embodiment is used for executing a moldheating step in order that the solidification of molten material isretarded and filling is smoothly performed. After molten material isfilled into the cavity, the mold heating-cooling system 1 in theembodiment is used for executing a mold cooling step for rapidlysolidifying molten material. The mold heating step and the mold coolingstep which are executed by the mold heating-cooling system 1 can beexecuted (started and stopped) together with a molding operation of themolding machine, for instance, based on a mold closing signal, aninjection signal, a pressure keeping signal, a mold opening signal ofthe molding machine.

When preheating is performed as mentioned above and a signal on amolding machine side or another heating start signal is received in thestandby state, a heating step for heating the mold 2 is executed and themold 2 is heated to the predetermined target heating temperature. Theheating step can be finished when the signal on the molding machine sideor another heat finish signal is received, or can be finished afterreaching the target heating temperature and the elapse of predeterminedtime.

When the heating step is finished and the predetermined time elapses orthe signal on the molding machine side or another cooling start signalis received, a cooling step for cooling the mold 2 is executed and themold 2 is cooled to the predetermined target cooling temperature. Thetarget cooling temperature can be inputted and set up through thedisplay operation portion 24.

In the embodiment, since the heat exchanger cooling valve 14 a whichsupplies or cuts off low-temperature medium (cooling medium) is providedfor the fluid passage on the low-temperature side of the heat exchanger20, the opening and closing control of the heat exchanger cooling valve14 a is performed during the cooling step. As in a second and a thirdembodiments mentioned below, in such an aspect without the heatexchanger cooling valve 14 a, the low-temperature medium (coolingmedium) can be constantly supplied to the fluid passage on thelow-temperature side of the heat exchanger 20.

In the example of the operation, the precooling step in which steam issupplied to the medium flow path 4 is executed before cooling medium issupplied to the medium flow path 4. In other words, in such a state thatthe cooling medium valve 12 a is closed, the steam valve 18 a is openedand steam is supplied to the medium flow path 4. When steam is suppliedas mentioned above, due to its contact to an inner circumferential faceof the medium flow path 4, the heat is absorbed, precooling isperformed, and steam is condensed in the heat exchanger 20. Thereby,pressure drops in the respective paths, i.e. the supply side path 13,the medium flow path 4, and the discharge side path 15. Namely, steamand cooling medium which is adhered to the inner circumferential face ofthe medium flow path 4 are gasified, successively condensed andliquefied in the heat exchanger 20, thereby the pressure in therespective paths sharply drops also accompanied with the backflowprevention portion 16 provided.

The above-mentioned precooling step can be executed in such a mannerthat the supply side path 13, the medium flow path 4, and the dischargeside path 15 are almost filled with steam. The precooling step can beexecuted until the predetermined time elapses or until a measurementpressure signal (detection pressure) of a detection means which detectsthe pressure in the paths such as a pressure sensor provided for any ofthe supply side path 13, the medium flow path 4, and the discharge sidepath 15 falls below the predetermined pressure (a threshold value). Inother words, when the pressure falls below the predetermined pressure,supply of steam can be switched into supply of cooling medium. Thepredetermined pressure, for instance, can be at which the next supply ofcooling medium is possible; it can also be appropriately set accordingto capacity (discharge pressure) or the like of the cooling mediumsupply pump 11. The predetermined pressure can be inputted and set upthrough the display operation portion 24.

In the precooling step, steam can be mixed with a small amount ofcooling medium and supplied, or air can be supplied instead of steam. Insuch a case, air can be mixed with a small amount of cooling medium orsteam and supplied.

After the above precooling step, a main cooling step in which coolingmedium is supplied to the medium flow path 4 of the mold 2 is executed.In other words, when the cooling medium supply pump 11 is activated, andthe steam valve 18 a is closed, the cooling medium valve 12 a is opened.The figure shows an example in which, considering rise time or the like,the cooling medium supply pump 11 is activated earlier than an openingof the cooling medium valve 12 a.

In the example of the operation, after a first cooling step constitutedby the main cooling step, a second cooling step in which air is suppliedto the medium flow path 4 of the mold 2 is executed. In other words,when the cooling medium valve 12 a is closed, and the air valve 19 a isopened, air is supplied to the medium flow path 4. On closing thecooling medium valve 12 a, the cooling medium supply pump 11 can bestopped. An aspect can be such that a bypass path which connects thesupply side path 12 with the discharge side path 15 (the cooling path 14in the figure) is provided, a bypass valve provided for the bypass pathis conversely opened and closed relative to the opening and the closingof the cooling medium valve 12 a, thereby generally activating thecooling medium supply pump 11 constantly.

The first cooling step and the second cooling step can be respectivelyexecuted until the predetermined time elapses in such a manner thatcooling medium in the medium flow path 4 is generally discharged(purged) by executing the second cooling step and without excessivecooling or the like; in other words, the temperature does not greatlyfall below the target cooling temperature on finishing the cooling step.Based on the detection temperature of the temperature sensor 6, thefirst cooling step can be switched into the second cooling step and thesecond cooling step can be finished; in other words, the air valve 19 acan be closed. In the second cooling step, in place of or in addition toair, a small amount of cooling medium can be intermittently supplied orsteam can be supplied as in an example of an operation in the secondembodiment mentioned below. In such a case in which steam is supplied, asmall amount of cooling medium can be intermittently supplied inaddition to steam. When steam or a small amount of cooling medium issupplied as mentioned above, the supply can be appropriately controlledin such a manner that the total amount in the medium flow path 4 almostgasifies and the medium in the medium flow path 4 almost does not remainat the end of the second cooling step. For instance, heat quantityreleased from an inner wall face of the medium flow path 4 is calculatedbased on capacity of the medium flow path 4, mold temperatures beforeand after filling of molten material such as resin; it can beexperimentally or empirically determined based on the heat quantity,gasification heat quantity of the medium, the target coolingtemperature, or the like. Since gasification occurs in a mold opening ora demolding step, a relatively small amount of remaining medium can beallowed.

After the cooling step, in the mold 2, the mold opening and thedemolding of the molded article are appropriately executed, and theheating step and the cooling step are repeatedly executed.

The heating step in which the mold 2 is heated and the cooling step inwhich the mold 2 is cooled, executed as mentioned above, improvetransfer property (transfer rate) of the cavity face to the moldedarticle and shorten the molding cycle.

The mold-cooling system 1 (the mold heating-cooling system) in theembodiment and the mold-cooling method (the mold heating-cooling method)which is executed by the mold-cooling system 1 constituted as mentionedabove enhance cooling efficiency while suppressing discharge of gasifiedcooling medium.

In other words, the discharge side path 15 connected to the outlet 5side of the medium flow path 4 of the mold 2 is communicated with theheat exchanger 20 condensing gasified cooling medium discharged from themedium flow path 4. Accordingly, gasified cooling medium is condensed inthe heat exchanger 20 and discharge of gasified cooling medium issuppressed. By condensing in the heat exchanger 20, pressure raised bygasification of cooling medium drops. Thereby, cooling medium is easilyfed into the medium flow path 4, cooling time is shortened, and coolingefficiency is enhanced.

In the embodiment, the discharge side path 15 on the downstream side ofthe heat exchanger 20 is constituted so as to return the medium to thecooling medium supply source 10, i.e. so as to circulate cooling medium.Accordingly, deposition of silica, scale, or the like into the mediumflow path 4 of the mold 2 or the like contained in cooling medium bygasification of cooling medium decreases as compared with theconventional one constituted in such a manner that cooling medium is notcirculated; new cooling medium is supplied and discharged. Thereby, themaintenance or the like of the medium flow path 4 is less frequentlyrequired.

In the embodiment, the discharge side path 15 on the downstream side ofthe heat exchanger 20 is provided with the backflow prevention portion16 for preventing backflow. Accordingly, when gasified cooling medium iscondensed in the heat exchanger 20, the pressure in the paths is moreeffectively dropped. Thereby, cooling medium is more easily fed into themedium flow path 4, cooling time is shortened, and cooling efficiency isextremely enhanced.

The backflow prevention portion 16 is not limited to the backflowprevention valve as in the figure and can be the opening and closingvalve or the like of which opening and closing are controlled by thecontrol portion 22. In such a case, an aspect can be such that, when apressure drop, associated with condensation in the heat exchanger 20, isdetected by the pressure sensor or the like, or a temperature detectedby the temperature sensor or the like falls below the predeterminedvalue, the opening and closing valve is opened and liquefied coolingmedium is discharged (returned).

As in the above-mentioned embodiment, the constitution can be such thatthe control portion 22 is provided to control the supply of steam or airand the supply of cooling medium and to supply cooling medium to themedium flow path 4 of the mold 2 after supplying steam or air to themedium flow path 4 of the mold 2. In other words, cooling medium can besupplied to the medium flow path 4 of the mold 2 after the precoolingstep in which steam or air is supplied to the medium flow path 4 of themold 2. As constituted above, the mold 2 is precooled by steam or airand cooling medium is more easily fed into the medium flow path 4thereafter. In other words, the heat of the medium flow path 4 of themold 2 is absorbed by the medium gasified by mixing the medium withsteam or air. The above gasified medium is condensed in the heatexchanger 20 and the pressure drops, thereby more easily feeding coolingmedium into the medium flow path 4.

As in the above-mentioned embodiment, the constitution can be such thatthe control portion 22 is provided to control the supply of steam or airand the supply of cooling medium and to supply steam or air to themedium flow path 4 of the mold 2 after supplying cooling medium to themedium flow path 4 of the mold 2. In other words, after the firstcooling step in which cooling medium is supplied to the medium flow path4 of the mold 2, the second cooling step in which steam or air issupplied to the medium flow path 4 of the mold 2 can be executed. Asconstituted above, cooling medium remained in the medium flow path 4 ofthe mold 2 is purged, the heat is absorbed by contacting the medium flowpath 4, and the mold 2 is cooled. Thereby, the remaining medium in themedium flow path 4 of the mold 2 decreases and heating is effectivelyperformed.

One example of the mold-cooling system in another embodiment of thepresent invention and one example of the mold-cooling method executedwith the example of the mold-cooling system in another embodiment of thepresent invention are explained.

FIG. 3 and FIG. 4 illustrate the mold-cooling system in the secondembodiment and the mold-cooling method executed with the mold-coolingsystem in the second embodiment. Differences from the first embodimentare mainly explained and common constitutions are allotted with the samereference numerals and their explanation is omitted or brieflyexplained. And an explanation of common operations with the example ofthe operation mentioned above is omitted or briefly explained.

Also in the embodiment, a mold-cooling system 1A is a moldheating-cooling system 1A which performs heating in addition to coolingof the mold 2.

The embodiment mainly differs from the above-mentioned first embodimentin that the steam supply path 18 supplying steam from the steam source 8is not connected to the supply side path 13, the cooling path 14communicated with the fluid passage on the low-temperature side of theheat exchanger 20 is not provided with the heat exchanger cooling valve14 a, and the discharge side path 15 on the downstream side of the heatexchanger 20 is not provided with the backflow prevention portion 16.

In the embodiment, the supply amount of cooling medium from the coolingmedium supply source 10 is able to be regulated. In the figure, theupstream supply side path 12 connected to a medium feeding side of thecooling medium supply source 10 is provided with a small flow path 12 bin a parallel manner; the small flow path 12 b is provided with a valvefor a small amount of cooling medium 12 c which supplies or cuts offcooling medium. In other words, when the cooling medium valve 12 aprovided for the upstream supply side path 12, i.e. a main path, isclosed and the valve for a small amount of cooling medium 12 c of thesmall flow path 12 b is opened, a relatively small flow amount ofcooling medium is supplied. The valve for a small amount of coolingmedium 12 c is connected to the control portion 22 through the signalline or the like similar to the other valves and the opening and closingcontrol is performed by the control portion 22.

In place of the above, an aspect can be such that a flow amount controlvalve or the like capable of controlling an opening degree is providedas the cooling medium valve 12 a.

One example of the mold heating-cooling method (the mold-cooling method)as one example of basic operation executed in the mold heating-coolingsystem 1A in the embodiment constituted as above is explained based onFIG. 4.

Also in a graph of FIG. 4, the horizontal axis is the time axis, thevertical axis is the detection temperature of the temperature sensor 6,and its transition is schematically shown the same as above.

First, the preheating step can be executed and the heating step can beexecuted in the same manner as above.

After that, the cooling step which cools the mold 2 can be executed.

In the example of the operation, cooling medium is supplied to themedium flow path 4 of the mold 2 without executing the precooling stepin which steam or air is supplied to the medium flow path 4 of the mold2. In other words, when the cooling medium supply pump 11 is activatedand the cooling medium valve 12 a is opened, cooling medium from thecooling medium supply source 10 is supplied to the medium flow path 4 ofthe mold 2. The figure shows, the same as above, an example in which thecooling medium supply pump 11 is activated earlier than the opening ofthe cooling medium valve 12 a , considering the rise time or the like.

In the example of the operation, after the first cooling stepconstituted by the main cooling step, the second cooling step in which asmall flow amount of cooling medium and air are intermittently suppliedto the medium flow path 4 of the mold 2 is executed. In the example ofthe operation, the cooling medium valve 12 a is closed; the valve for asmall amount of cooling medium 12 c is intermittently opened; the smallflow amount of cooling medium is intermittently supplied to the mediumflow path 4 of the mold 2; and after that, the air valve 19 a isintermittently opened and air is intermittently supplied to the mediumflow path 4 of the mold 2. When the valve for a small amount of coolingmedium 12 c is closed, the cooling medium supply pump 11 can be stopped.In place of the above aspect, an aspect in the second cooling step canbe such that air valve 19 a is intermittently opened and air isintermittently supplied to the medium flow path 4 of the mold 2; andafter that, the valve for a small amount of cooling medium 12 c isintermittently opened and the small flow amount of cooling medium isintermittently supplied to the medium flow path 4 of the mold 2. Andfurther after that, the air valve 19 a can be intermittently opened andair can be intermittently supplied to the medium flow path 4 of the mold2. Or an aspect can be such that the valve for a small amount of coolingmedium 12 c and the air valve 19 a are alternately opened, and the smallflow amount of cooling medium and air are alternately supplied to themedium flow path 4 of the mold 2.

In the example of the operation, when the detection value of thetemperature sensor 6 as mentioned above falls below the predeterminedthreshold value (a switching threshold value), the first cooling step isswitched into the second cooling step. The setting of the switchingthreshold value and the execution control of the second cooling step canbe appropriately performed in such a manner that, the same as above,cooling medium in the medium flow path 4 is almost discharged (purged)by executing the second cooling step and excessive cooling or the likeis not caused; in other words, the temperature does not greatly fallbelow the target cooling temperature at the end of the cooling step. Theabove-mentioned switching threshold value can be inputted and set upthrough the display operation portion 24. In the above-mentioned secondcooling step, steam can be supplied in place of or in addition to air asmentioned above.

Also in the example of the operation, the precooling step as mentionedabove can be executed.

Also in the example of the operation, after the cooling step, in themold 2, the mold opening and the demolding of the molded article areappropriately executed, and the heating step and the cooling step arerepeatedly executed.

Also in the mold-cooling system 1A (the mold heating-cooling system) inthe embodiment and the mold-cooling method (the mold heating-coolingmethod) which is executed by the above system, an effect substantiallysimilar to the above-mentioned first embodiment and the example of theoperation in the first embodiment is obtained.

One example of the mold-cooling system in still another embodiment ofthe present invention and one example of the mold-cooling method whichis executed by the example of the mold-cooling system in still anotherembodiment of the present invention are explained below.

FIG. 5 illustrates the mold-cooling system in the third embodiment andthe mold-cooling method which is executed by the mold-cooling system inthe third embodiment.

Differences from the above-mentioned respective embodiments are mainlyexplained and common constitutions are allotted with the same referencenumerals and their explanation is omitted or briefly explained.

Also in the embodiment, a mold-cooling system 1B is a moldheating-cooling system 1B which performs heating in addition to coolingof the mold 2.

In the embodiment, a cooling path 14A which supplies cooling medium to afluid passage on a low-temperature side of a heat exchanger 20A is notcommunicated with the cooling medium supply source 10 which suppliescooling medium to the medium flow path 4 of the mold 2 but iscommunicated with a cooling medium supply source 17 for the heatexchanger 20A. As constituted above, the cooling medium supply source 17can be a cooling tower or the like installed in the plant or the likeand the cooling medium supply source 10 can be the storage portion orthe like in which temperature control is not performed, therebysimplifying the constitution of the cooling medium supply source 10.

Also in the mold heating-cooling system 1B in the embodiment, operation(the mold heating-cooling method (the mold-cooling method))substantially similar to those in the above-mentioned respectiveembodiments is executed; an effect substantially similar to those in theabove-mentioned respective embodiments is obtained.

The heat exchanger 20, 20A is not limited to such an aspect in whichcooling is performed by feeding cooling medium into the fluid passage onthe low-temperature side; for instance, gasified cooling medium which isfed into the fluid passage on the high-temperature side can be condensedby cooling with a fan or the like, i.e. an air cooling type.

The above-mentioned constitutions, operations, or the like which aredifferent from each other can be appropriately recombined or combined,or appropriately modified as needed.

In the above-mentioned respective embodiments, while an aspect is shownthat the discharge side path 15 on the downstream side of the heatexchanger 20, 20A is connected to the medium returning side of thecooling medium supply source 10 and cooling medium is circulated, anaspect can be such that the discharge side path 15 on the downstreamside of the heat exchanger 20, 20A is not connected to the mediumreturning side of the cooling medium supply source 10 and cooling mediumis discharged as drain.

In the above-mentioned respective embodiments, the mold heating-coolingsystem 1, 1A, 1B which performs heating in addition to cooling of themold 2 is shown but can be the mold-cooling system 1, 1A, 1B whichperforms cooling of the mold 2. In such a case, a mold-heating system (amold-heating apparatus) which is controlled separately from themold-cooling system 1, 1A, 1B and performs heating of the mold 2 can beprovided.

In the above-mentioned respective examples of the operation, an examplein which, after the first cooling step in which cooling medium issupplied to the medium flow path 4 of the mold 2, the second coolingstep in which steam or air is supplied to the medium flow path 4 of themold 2 is shown; however the second cooling step can be omitted. In sucha case, the cooling step can be such that the precooling step asmentioned above is executed and then the main cooling step is executed,or furthermore only the main cooling step is executed. In other words,in order that the pressure is dropped, cooling medium is effectivelysupplied, and cooling is performed, the discharge side path 15 connectedto the outlet 5 side of the medium flow path 4 of the mold 2 can becommunicated with the heat exchanger 20, 20A and gasified cooling mediumdischarged from the medium flow path 4 can be condensed in the heatexchanger 20, 20A.

DESCRIPTION OF THE REFERENCE NUMERAL

1, 1A, 1B mold heating-cooling system (mold-cooling system)

2 mold

3 inlet

4 medium flow path

5 outlet

8 steam source

9 air source

10 cooling medium supply source

12,13 supply side path

15 discharge side path

16 backflow prevention portion

18 steam supply path

19 air supply path

20, 20A heat exchanger

22 control portion

1. A mold-cooling system for cooling a heated mold by supplying coolingmedium from a cooling medium supply source to a medium flow pathprovided for a mold, wherein a discharge side path connected to anoutlet side of the medium flow path of the mold is communicated with aheat exchanger condensing cooling medium gasified and discharged fromthe medium flow path.
 2. The mold-cooling system according to claim 1,wherein a path supplying steam from a steam source or air from an airsource is connected to a supply side path connected to an inlet side ofthe medium flow path of the mold from the cooling medium supply source,and wherein the mold-cooling system comprises a control portioncontrolling supply of steam or air and supply of cooling medium, andsupplying cooling medium to the medium flow path of the mold aftersupplying steam or air to the medium flow path of the mold.
 3. Themold-cooling system according to claim 1, wherein the path supplyingsteam from the steam source or air from the air source is connected tothe supply side path connected to the inlet side of the medium flow pathof the mold from the cooling medium supply source, and wherein themold-cooling system comprises the control portion controlling the supplyof steam or air and the supply of cooling medium, and supplying steam orair to the medium flow path of the mold after supplying cooling mediumto the medium flow path of the mold.
 4. The mold-cooling systemaccording to claim 1, wherein the discharge side path on a downstreamside of the heat exchanger is provided with a backflow preventionportion preventing backflow.
 5. The mold-cooling method for cooling aheated mold by supplying cooling medium to a medium flow path providedfor a mold, wherein a discharge side path connected to an outlet side ofthe medium flow path of the mold is communicated with a heat exchanger,and cooling medium gasified and discharged from the medium flow path iscondensed in the heat exchanger.
 6. The mold-cooling method according toclaim 5, wherein cooling medium is supplied to the medium flow path ofthe mold after executing a precooling step in which steam or air issupplied to the medium flow path of the mold.
 7. The mold-cooling methodaccording to claim 5, wherein a second cooling step in which steam orair is supplied to the medium flow path of the mold is performed afterexecuting a first cooling step in which cooling medium is supplied tothe medium flow path of the mold.
 8. The mold-cooling system accordingto claim 2, wherein the control portion controls the supply of steam orair and the supply of cooling medium, and supplies steam or air to themedium flow path of the mold after supplying cooling medium to themedium flow path of the mold.
 9. The mold-cooling system according toclaim 2, wherein the discharge side path on a downstream side of theheat exchanger is provided with a backflow prevention portion preventingbackflow.
 10. The mold-cooling system according to claim 3, wherein thedischarge side path on a downstream side of the heat exchanger isprovided with a backflow prevention portion preventing backflow.
 11. Themold-cooling system according to claim 8, wherein the discharge sidepath on a downstream side of the heat exchanger is provided with abackflow prevention portion preventing backflow.
 12. The mold-coolingmethod according to claim 6, wherein a second cooling step in whichsteam or air is supplied to the medium flow path of the mold isperformed after executing a first cooling step in which cooling mediumis supplied to the medium flow path of the mold.